Development of an Effective Flared Guardrail Terminal
Brian Pfeifer, John Reid, Bavneet Brar
The Breakaway Cable Terminal (BCT), which has been used for a number of years to terminate w-beam guardrail in Kansas and a number of other states, does not always perform adequately when impacted by small vehicles. As a result of this poor performance, it has recently been disallowed by the FHWA for use on high speed, high volume roads on the National Highway System. Several modifications have been made to improve the performance of this terminal over the years, but no non-proprietary system has met with much success. The Kansas Department of Transportation (KDOT), and other states, felt that there was a need for a non-proprietary end terminal which met the current crash test standards of Test Level 3 of NCHRP Report 350. As a result of this interest, this study was initiated to develop a non-proprietary guardrail end treatment which would satisfy the current safety standards. Computer simulation and component testing was undertaken to evaluate the concept of flattening areas of the rail used in the terminal in order to reduce the force required to buckle the rail. Several dynamic bogie tests as well as one full-scale test were conducted. The design selected for evaluation under full scale crash test conditions consisted of a thrie beam flattened at two locations. The thrie beam was selected for testing because it had the best potential for successfully redirecting a pickup at 100 km/h and 20 degrees, as required by the new NCHRP Report 350 test criteria. Although the full-scale vehicle crash test failed to meet the required criteria, it was determined that this concept had the potential for success.
Highway Safety, Crash Tests, Guardrail, W-Beam, Thrie Beam, Terminal, End-Treatment
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